Oil well pumping assembly



April 20, 1937.

E. Q. BENNETT OIL WELL PUMPING ASSEMBLY Mza. ATTORNEY Filed March 17. 1933 '30 stresses Patented Apr. 20, 1937 on.l WELL PUMPING ASSEMBLY Edwin O. Bennett, Ponca City, Okla., assignor t9 Continental Oil Company, Ponca City, Okla., a corporation of Delaware Application March 17, 193s, serial No. 661,221

2 Claims.

My invention relates to an oil well pumping assembly and more particularly to an assembly in which the stroke acceleration of the oil Well pump rods is controllable.

One of the largest expenses in connection with the pumping of oil wells with standard deep Well sumps and sucker rods is rod breakage. In the ordinary set up for pumping, the pumpy barrel is placed on the bottom of a string 'of tubing lo which may be as deep as 5,000 feet in some wells. The plunger which works inside the pump barrel is actuated by a string of rods from to 1 in diameter depending upon the loads to handled. The rods are given a recipro- 15 eating motion by the up and down swing of the end of a walking beam supported by a Samson post at the center of the beam, and connected to a rotary crank through a. pitman rod at the other end. The crank, which may have a throw zo of up to 36" is connected to the end of a shaft which carries a large pulleyor band wheel.

'I'he prime mover, which may be a steam or internal combustion engine or an electric motor, is connected to the band wheel by a belt, either 25 directly or through a jack shaft speed reducer.

The'motion of the crank is constant and sets up a true harmonic motion in the rods. The acceleration of the pump rods due to the circular motion of the crank imposes very high shock at the start of the up stroke of the plunger. 'I'hese stresses are sometimes partially offset by counterbalanclng the weight of the rods with weights on the beam, pitman or crank. The crank weight which is generally used acts 35 as a flywheel on the shaft and while it takes the power peaks from the prime mover it often adds increased s hock stresses in the pump rods, shortening their life and increasing operating costs. The type of pumping operation which 40 will give the most economy is one in which the variation in stresses in the pump rods is kept to a minimum.

One object of my'invention is to provide a pumping assembly for pumping oil wells in which 45 means are interposed between the prime mover and the sucker rods to control vthe stroke acceleration.

Another object of my invention is to provide an assembly for pumping oil Wells in which the 50 beginning of the up stroke of the plunger will be slow. y

A further object of my invention is to provide an assembly in which the up stroke ofthe sucker rods will commence slowly and will be gradually accelerated.l

(Cl. 10S-45) Another object of my invention is to provide a pumping rod assembly in which the sucker rods will have a rapid down stroke.

Further objects of my invention will be apparent from the following description.

In the accompanying drawing which forms part of the instant specification and which is to be read in conjunction therewith and in which like reference numerals are to be used to indicate like parts in the various views;

Figure 1 is an elevational view showing my assembly.

Figure 2 is a detailed side elevation of the stroke varying mechanism.

Figure 3 is an end view of the detail shown in Figure 2.

Figure 4 is a fragmentary sectional view of the stroke varying mechanism.

Figure 5 is a detailed fragmentary sectional view of a portion of the stroke varying mechanism.

Figure 6 isl another detailed fragmentary sectional view of a portion of the stroke varying mechanism.

In general, my invention contemplates the use of a hydraulic unit known to the trade as the Waterbury speed gear. This is well known in the art and consists of a constant speedv motor driving a, hydraulic generator. 'I'he hydraulic pressure created by the generator is used to drive a hydraulic motor. The speed reduction is obtained by varying the stroke of the pistons in the hydraulic generator by means of a tilting plate. The hydraulic generator end is usually referred to as the A end and the hydraulic motor end is usually referred to as the B end. I propose to interconnect the A and B ends by a suitable train of mechanical movements in which a cam is interposed. The-B end of the motor is connected to a suitable pulley which is connected to a band wheel by means of belting. The band wheel drives the walking beam in the usual manner. A

Thearrangement is such that, when the sucker rods are moving down, the tilting box, `which controls the speed ratio between the A 'and B ends is tilted to a greater angle than is the case when the sucker rods are moving up. This will result in a rapid down stroke, accompanied by a slow up stroke. The movement is such that, when the rods and the load 'of oil start moving upwardly, the speed of travel will be less. A greater acceleration is permitted until the top of the up stroke'is reached. This acceleration not under a load. In this manner, unusual stresses are avoided. In a customary type of apparatus in which the reciprocation is with simple. harmonic motion, the up stroke will be at the 5 point of greatest velocity which is the cause of undue stresses.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features vand 10 sub-combinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is',

15 therefore, to be understood that my invention is not to be limited to the speciilc details shown and described.

Having thus described my invention, what I claim is:

20- 1. In an oil well pumping assembly, a prime mover, a hydraulic generator driven thereby, a control means for varying the output of said generator, a rotary hydraulic motor driven by said generator, a pump rod, means driven by said hydraulic motor for reciprocating said pump rod, a rotary cam, means driven by said motor for rotating said cam, and means driven by said cam for actuating saidgenerator control means, the construction of the cam being such that the up stroke of the pump rod will commence slowly and be gradually accelerated.

2. In an oil well pumping assembly, a primey mover, a hydraulic generator driven thereby, a control means for varying the output of said generator, a rotary hydraulic motor driven by said generator, a pump rod, means driven by said hydraulic motor for reciprocating said pump rod, a rotary cam, a cam follower, means driven by said motor for rotating said cam, means actuated by said follower for moving said generator control means and means for adjusting the motion of said follower, the construction of the cam being such that the loaded strokeof the pump rod will commence slowly and be gradually accelerated.

EDWIN O. BENNETT. 

